Counting roughly nine months backwards, that puts the most popular date of conception around December 17 — right before the holidays and a nice time to be under the covers as the temperatures drop outside.

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Actor Adam Sandler shares the most popular birthday, Sept. 9.

A less scientific metric is the sheer volume of famous people born on this date.

As Time Magazine points out, though, a previous Harvard University study looking at birth data between 1973 and 1999 pegged Sept. 16 as the most common birthday.

Regardless, the Daily Viz map confirms that September continues to be a very popular month to give birth to a child — and December, by extension, the most popular time to make one. The top 10 most common birthdays all fall in the first month of fall.